<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>练习</title>
    <script src="static\js\jquery-3.7.1.min.js"></script>
</head>
<style>
    div{
        width: 200px;
        height: 200px;
        background-color: blue;
    }
</style>
<body>
    <div></div>
    <script>
        console.log($("div").css("width"));
        $("div").css("width","300px");
        console.log($("div").css("width"));
        $("div").css({
            width:400,
            height:400,
            backgroundColor: "red"
        });
        console.log($("div").css("backgroundColor"));
    </script>
</body>
</html>